Wax compositions



Patented May 2, 1950 ICE WAX COMPOSITIONS John R. Bowman and William P.Ridenour, Pittsburgh, Pa., assigncrs to Gulf Research & DevelopmentCompany, Pittsburgh, Pa, a corporation of Delaware No Drawing.Application June 7, 1946, Serial No. 675,318

Claims.

This invention relates to improved wax compositions and moreparticularly to paraffin wax compositions containing an additive toincrease the tensile strength thereof.

Paraffin wax and paraffin wax products are used in many industries. Inmany of its applications and particularly in coating paper for such usesas wrapping, it is desirable to have as high a tensile strength aspossible while at the same time retaining all of the desirablecharacteristics of a substantially pure parafiin wax. These otherdesirable characteristics include a high melting point, a uniformcrystalline structure, and freedom from scuffing and mottling.

An object of the present invention is to provide paraifin waxcompositions with increased tensile strength.

A further object of the invention is to provide an improved paraflin waxcomposition with increased tensile strength while at the same timeretaining the other desirable features of paraffin wax.

These and other objects of this invention are achieved by a, compositioncomprising paraffin wax and from about 0.1 per cent to about 0.5 percent by weight of a wax-soluble aluminum soap.

The method for obtaining the improved wax comprises thoroughly mixingparaffin wax in a molten state with the aluminum soap.

Of the aluminum soaps useful in the invention, aluminum stearate ispreferable. Aluminum soaps of other fatty acids may be used so long asthey are wax-soluble. These include the saturated fatty acid soaps inthe range above C12.

The amount of the aluminum soap to be added may be varied, between about0.1 per cent and about 0.5 per cent; 0.5 per cent is preferable. Whileamounts varying slightly from either of these limits may give somedesirable results, amounts substantially larger than 0.5 per cent areundesirable. For example, at 0.75 per cent aluminum stearate in paraifinwax does not form a true solution, but by vigorous stirring a colloidalsuspension may be obtained. Distinct plastic properties are evident andon brief standing a gel is formed which on re-stirring breaks up to givea distinctly non-homogeneous mixture.

The aluminum stearate used in the composition should be the di ortri-stearate, the monostearate showing no improvement as it ispractically insoluble in the paraflin wax. The aluminum di ortri-stearate may be any of the products commercially available, but aswill be seen from the test data below, that which is free of fatty acidis most desirable. It may be necessary to treat the commercial aluminumstearates by washing with a fatty acid solvent such as absolute ethylalcohol, acetone,ethylacetate, etc. to remove the free acid.

The various types of parafiln wax may be improved according to thepresent invention, but the invention is particularly applicable to thegrades of paraffin wax low in oil content. Improvement has been noted ina refined 122 F. ASTM melting point paraffin wax, but the highesttensile strength has been obtained with a highly refined parafiin waxhaving an ASTM melting point of 132 F.

The wax composition may contain other ingredients than paraffin andaluminum soaps but it will be understood that these ingredients shouldnot be of a type or quantity that will substantially reduce the tensilestrength, such as for example, oil.

The table below illustrates the tensile strength results obtained with ahighly refined paraffin wax having an ASTM melting point of 132 F. Thealuminum stearate used had the free fattyacid content indicated in thetable and the acidfree samples were obtained by washing with ethylalcohol.

TABLE Blends of aluminum stearate and pamfiin war (132 F. E. M. P.)

Lbs. improvement oi acid-free over commercial stearate Lbs. improvementof blend over straight wax Free Fatty content of soap, per cent Tensilestrength F. Lbs. pull Per cent Added It will -be seen fromtheabove"table'rthat' the commercial di-stearate is more effective'than thetri-stearate, but this is apparentl for the reason that the free acidcontent of the tri-stearate is substantially higher. acid, thetri-stearate becomes the more efiective additive.

The preferable compositiongis a'highly refined paraiiin wax containingabout 0.5 per cent of Free fatty acids not only reduce the tensilestrength of the waX, but tend to cause the wax to crumble, increasescuffing and causeinottling. These effects oppose the desirable onesinduced -.by. aluminumsoaps;..therefore aluminum soaps as -lowaspossiblein freejfatty .acid contents are deisirable. However,commercial aluminum soaps ..WhiQhcontain .free fatty acids in the,ordinary amounts .are .tolerable.

;,The.,-addition ofthe above specified amount of ,the. aluminum soap.tothe .parafiinwax increases the tensilestrengthand reducesmottling,asset .forth above. Inaddition, opacity is considerably increased as isalso ductility. Paraffinwaxes containing-aluminum soaps will standconsiderably greater stretchingand bending before breaking than.parafiin waxes without the aluminum soap. ..'-Ihev texture of thewaxsurface is. slightly altered, becomingnnctuous or soapy to. the touchand hav- Hing. less tendency toscuff under mild abrasion.

Asolid parafiin Wax composition'of increased tensile strengthconsisting. essentially of parafiin wax .and from about..0..1. per .centto about 015 per acentrof; aluminum .stearate wherein. there, are. atleast two stearate .radicals .per; aluminum atom 7 and saidaluminumstearate. issubstantiallyjfree rot-acid.-

-2., '.A...solid.- paraifin .wax composition .01" .inyer-easedtensilestrength consisting essentially .lo'f refined "paraffin wax :andabout .025 .per .cent .of

On removal of itheifree :aluminum t'ri-stearatesubstantiallyiree ofacid.

*3. A solid paraffin wax composition of increased tensile strengthconsisting essentially of refined stearate substantially free of acid.

4. -A'method forrmakinga composition consisting-essentially of-solidparaflin wax of increased tensilestrength comprising washing acommeraluminum tri-stearate substantially free of acid. n cial aluminumtri-stearate with ethyl alcohol unillil it is substantially acid-freeand mixing it with rmoiten paraffln wax in proportion such that the waxcontains from about 0.1 per cent to about 0.5 per center" said aluminumtri-stearate.

5. A method fol-making a composition consisting essentially of-solidparaffin wax of "increased "tensile strength'comprising washing acommercial aluminum-*stearate wherein thereare at least two ,stearateradicals for each aluminum atom with asolvent until it is substantiallyacid-free JOHN R. BOWMAN. WILLIAM P. RIDENOUR.

' REFERENCES CITED 7 The following, references are of record in the fileofthis patent:

UNITED STATES PATENTS Number "Name Date 2,130,560 "Plechner Sept. 20,1938 2,32 O;"l4. Nill Junel, 1943 2,359,946 Sudholz et a1. Oct; 10, 1944OTHER .REFERENCES 1 Metallic 'Soaps',published. by Metasap Chemical

1. A SOLID PARAFFIN WAX COMPOSITION OF INCREASED TENSILE STRENGTHCONSISTING ESSENTIALLY OF PARAFFIN WAX AND FROM ABOUT 0.1 PER CENT TOABOUT 0.5 PER CENT OF ALUMINUM STEARATE WHEREIN THERE ARE AT LEAST TWOSTEARATE RADICALS PER ALUMINUM ATOM AND SAID ALUMINUM STEARATE ISSUBSTANTIALLY FREE OF ACID.